System of distribution



March 26, 1929. M. E. REAGAN I SYSTEM OF DISTRIBUTION Filed 001;. 5, 1923 a man m m w v A we m Wm M w WITNESSES:

Patented Mar. 26, 1929.

' UNITED STATES ,106,705 PATENT *-oFFlc-E. f

- MAURICE n. REAGAN, orrrr'rsnunen, PENNSYLVANIA, Assienon 'ro' W'ns'rme- HOUSE ELECTRIC & MANUFACTURING con-tame A eomom on or PENNSYLJ VANIA.

SYSTEM or D-IS'I'RI-BUTION.

Application filed October 5, 1923. Serial m. 666,766.

a system of control for transferring a feeder circuit from a main busto an auxiliary bus,

' when the feeder circuit becomes shorten 'cuited, and for retransferring the feeder circuit to the main bus when. the short-circuited conditions are cleared. Another object of my invention is to provide a system of the above-indicated character that shall properly measure the resistance ofthe feeder" circuit to determine Whether a circuit shall be retransferred to the main bus, irrespective of the variations in the voltage of the auxiliary bus.

A further object of my invention is to v value of current that will traverse the feeder provide connecting means between the main and the auxiliary bus that shallserve to (11$- connect the two buseswhen a sustained abnormal condition of the feeder circuit causes a transfer of excessive currents to the auxil iary bus from the main bus.

Another object of my invention is to provide a control system in a system of distribution whereby a feeder circuit, when ground-- ed, may be transferred from a main bus from which it is normally energized, to an auxil-- Energy is then supplied to the feeder circuit to burn clear the faulty condition such as a short circuit caused by the grounding of the feeder circuit conductor.

In order to obtain suflic'ient energy for the purpose of burning clear the fault in the feeder circuit, energy may be, supplied to the auxiliary bus from the main bus through a limiting resistor or from an incoming feeder circuit from anadjoining station, or from both the main bus and the incoming feeder circuit. Then the faulty feeder circuit is transferred to the auxiliary bus, resistance-measuring means are ren I dered eife'ctive to measure the resistance of the feeder circuit conductor and the-e0nnected load and thereby to detect the clear- 'ance of the faulty condition." When the feeder circuit is cleared ofthe faulty cond1t1on, the resistance measuring means automatically effects the transfer of the feeder circuit to the main bus.

.; Sincetheauxiliary bus may be supplied with energy from the main bus or from 'an incoming feeder circuit or from both, it is obvious that the voltage of the auxiliary bus may varyconsiderably. Moreover, the transfer of an additional faulty feeder circuit to the auxiliary bus will tend still fur- 1tJher to affect the voltage of the auxiliary Since the faulty feeder circuit is supplied with current from the auxiliary bus, the

circuit depends upon the value of the voltage of theauxiliary bus. In measuring the resistance of the feeder circuit, it is therefore necessary to take intoaccount the variation of the voltage of the main bus and to compensate for such variation. The'voltage of the main bus,being substantially constant,

cannot be'utilized to energize the resistancemeasuring device sinc'e there is no relation between the current in the feeder circuit and the voltage of the main bus.

In order to obtain the correct measure of the resistance "of the feeder circuitand its connected load, I providea relay device of 'a balance type embodying a balancing arm and twosolenolds operating thereon, to con trol the opening of a switching device for an external circuit. One coil is energized in accordance with the current traversing the feeder circuit and the other coil is energized in accordance with the voltage of the auxiliary bus.

For any constant voltage on the auxiliary bus, the current traversing the current coil on the relay device will decrease in proportion as the resistance of the feeder circuit increases; \Vhen the current decreases to a predetermined value corresponding to the voltage of the auxiliary bus atthat time, to indicate a predetermined value of resistance in the feeder circuit, the torque of the voltage coil will be s'uflicient to overcome that of the current coil and the relay device will operate toeffect the retransfer of the feeder circuit from the auxiliary bus to the main bus.

For any constant value of resistance in the feeder circuit, an increase in the voltage of the auxiliary bus will effect a correspond-- rect measure of the resistance the feeder circuit may thus be taincd, irrespective of the voltage of the auxiliary bus.

If one or more faulty feeder circuits be transferred to the auxiliary bus and the current transferred to that bus from the main bus, through the resistor, exceeds the continuous current-carrying capacity of the resistor, a tempe'ature-responsive device that is associated with, and influenced by, the resistor, will effect the opening of the resistor circuit, to preclude the further transfer of current therethrough while in this overheated condition.

Figure 1 of the accompanying drawing is a diagrammatic view of an electrical system embodying my invention.

Fig. 2 is a schematic diagram illustrating the arrangement of a main switching device and two adjacent substations. s

Fig. 31s a simplified illustration of the disposition of a resistance-n'ieasuring relay that is employed in the system which is illustrated in Fig. 1.' I

In Fig. 1, a feeder circuit is supplied with energy from a main bus conductor 11 or trom.anauxiliary bus conductor 12 wh ch may derive its energy from the main bus conductor 11 through a resistor 13, or from an incoming feeder circuit 14.1 1011] an adjacentstatioii or substation.

The feeder circuit 10 may be connected to the main bus conductor llllllOllgli the main contacts of a switching device 15, orlit may be connected to the auxiliary bus conductor 12 through the main contacts of a switching device 16.

The switching device 15 is provided with two auxiliaryinterlock switches 17 and 18, the former ofwhich is closed, and the latter of which is open, when the switching device I is deenergized. The switching device 16 comprises, in addition to its main switch and its operating coil, two interlock switches 19 and 20 that are closed when the switching The increase in the amperedevice is open, and an interlock switch 21 that is open when the switching device is open.

The operation of the switching device 15 is controlled by. a control switch 23 comprising, in addition to its operating coil, a switch 24 that is closed when the operating coil is deenergized, and aswitch 25 that is open when t-heoperating coil is deenergized.

Similarly, a control switch 26 is provided to control the operation of the switching device 16, and is provided with but one set of contact members. 1 x

In order to detect an abnormal condition, such as a short-circuit condition, in the feeder circuit 10, I provide a current transfornier28, a solenoid relay 2!) that is sensitive enough torespond quickly to the impfulse delivered by thecurrent transformer,

. and a holding relay 30 which serves to main tain the tripping circuit initially set up by the sensitive relay 29. The holding relay 30 is provided with a front interlock switch 2151 that closes when the relay is energized.

I In order to provide control energy for relay devices that are einployed'in a station containing'th'e system described, three sets of bus conductors are provided. One set of conductors32 and 33 have 600 volts inipressed thereacross from the main bus 11 through a switch 34 which may be used to control the energy to the control conductors. A second set of control conductors 35 and 36 are employed having a potential difference of 240 volts and a third set of control conductors 37 and 38 are employed, having a potential difference of 92 volts.

During normal conditions on the feeder circuit 10, tlie'switching device 15 is closed to connect the feeder circuit 10 to the main bus 11, as more fully sctforth hereinafter.

Upon the occurrence of abnormal conditions on the feeder circuit 10, the current transformer 28 delivers an impulse to the relay 29 which operates to complete a circuit from the conductor 36 through the operating coil of holding relay 30, the back interlock switch 26 of the switching device 16 and the interlock switch 18 of the switching device 15 to the control conductor 35. lay 30 is thereupon energized to close its main switch and its auxiliarv switch 211. The

-]11tllIl S\\'.itCll 30 of the holding relay maintains the circuit that broken by the relay The holding re 29 immediately after its operation. and the interlockswitch 31, in closing, short circuits the operating coil of the control relay by connecting both terminals of the coil to the bus conductor 36. The control relay 23 is thereupon deenergized to permit its interlock switch 24 to close, and its switch 25 to open. i

The interlock switch 25 opens the circuit of the operating coil of the switching device 15, whereupon the latter opens to disconnect the feeder circuit from the main bus conductor 11. Y I l Simultaneously, the interlock switch 2 1,111 closing, completes the circuit of the operating coil of control relay 26. That c "suit "auxiliary bus 12.

may be traced'from the control conductor 33 through the switch 24, the operating coil of the relay 28 and the bacl-z interlock switch 17 of the main switch late the control con ductor e "The" control relay 26 is thereupon energlued to'close its switch, Wnereupon the circuit is completed to energize the operating coil of the switching device 16 to connect the feeder'circuit 10 to the auxiliary bus 12. I

That circuit may be traced from the control conductor 32 throu h the back interlock switch 17 of, the main switcljiing device 15,-

the relay switch 26 andthe operating coil of the switching device 16 to the control conductor Switching device 16 thereupon closesto connect the feeder circuitlt) to'the Energy is now transmitted to the feeder circuit lO'from the main bus 11 through the auxiliary bus 12 and resistor 13, which is connected between both bus conductors 11 and 12'by a switch 40. If the conditions in thefeeder circuit 10 are such that abnormal currents are drawn from the main bus 11 through the resistor 13, a thermostat V 41 will operate to short circuitthe operating coil of an auxiliary relay switch 42, which normally maintains the connecting switch energized. Then the operating coil of the switch 12 is short circuited by the over heated thermostat 41, the connecting switch it) is opened, and the auxiliary bus 12 is disconnected from the main bus 11.

Simultaneously, with the closing of the switching device 16 to connect the feeder circuit to the auxiliary bus'12,'a resistanceineasuring device 45 is operatively connected between the feeder circuit 10 and the auxiliary bus 12.

.lhe resistmice-measuringdevice 45 com prises a balance arm, and two operating coils 7 16 and 4 7, which act upon the arm to control the opening or closing of a contactive device 4:8. The toil 4:6 is a current coil, and is energized from a shunt all) in the feeder circuit 10 in accordance with the value of current traversing that circuit.

The coils? is a potential COll and is connected between the auxiliary bus 12 and ground, through a vari- ,able resistor 50, and the front interlock' switch 21 of the switching device 16. The

resistance measuring device may be, calibrated by the resistor or by other suit able means for varying the current in the current coil. i

So long as the short-circuit conditions remain on the feeder circuit 10, current will traverse the circuit and the current coil 46 will be correspondingly energized.

Assuming the voltage of the auxiliary bus 12 to remain substantially constant, the'current in the feeder circuit 10 and, conse-"' 'quently, in the current coil 46 will vary in inverse proportionto the resistance of the feeder circuit and the connected load. Thus, as the resistance increases, the current will decrease, until the torque developed thereby will be overbalaneed by the torque of the potential coil, and the switching device will be: closed to effect the retransfer of the' feeder circuit- 10 from the auxiliary bus 12 to the main bus 11.

Since the current in the coil 46' and the voltageimpressed upon the coil 47 have a ratio, according to Uhms law, depending upon the value of the resistanceof the feeder circuit 12, it is readily apparent that variations in the voltage of the auxiliary bus 12.

will. be compensated for by means of the arrangement which I here employ. Thus for any definite value of resistance, an increase in the voltage of the auxiliary bus will cause a corresponding increase in the current in the feeder circuit and, consequently, in the current coil 16. f The relative conditions of the two operating coils and the torques developed thereby are therefore not changed by variations in the voltage of the auxiliary bus, but are affected only by variations in the resistance of the feeder circuit and the con necting load.

When the resistance of the feeder circuit and the connected load increases to a predetermined value at Which the torque developed by the voltage coil 47 exceeds the torque developed by the cu rent coil 46, the contactive device 48 is closed to connect the operating coil of the control switch 23 between the control conductors 35 and 36. The control. switch 23 thereupon opens its switch 24 and closes its switch 25.

The opening of the switch 24; interrupts the energizing. circuit the operating coil of the control switch 26, which, in turn, opens its switch 15, and the switch 25,which has been closed by the control switch as just described, to the control conductor 33. The switching device 15 is thus closed to reconnect the feedercircuit .10 to the main bus 11.

In order to provide for remote control of' the station by a system supervisor, three remaintain a holding, circuit for the relay wlnch may be tracer ot the main switch 15.

control coiuluctors 237 and 38. The rcla lay switches 52, 53 and 54 are provided. Re-

lay 52 controls the transfer of the feeder circuit from the main bus to the auxiliary bus. Relay 53 controls the locking out of the feeder circuit to prevent its connection to either bus. Relayofi controls the retransfer or reconnection of the feeder circuit to the main bus.

The relay switch 52, when energized, operates a relay s\ rch which is provided with two switches 56 and 57. The sw'tch 57, when closed, short rcuits the operating coil of the control relay 23, thereby deenergizir' that relay to ell ect the opening of the main switch 15.

The switch 56, when closed, serves to 55 i from the conductor 87 through an interlock switch 58 of the retranster relay switch and the switch of the .transter relay to the control conductor 38. The relay will thereupon remain energized to maintain the operating coil of the controlling relay 2? short circuited until released by the system supervisor by energizing the retranster relay Immediately after the opening of the main switch 15, the switch 16 is closed to connect the feeder circuit to the auxiliary bus conductor 12. 'hen the main switch 15 and the control relay 23 are dcenergizod the back interlock switch 17 of the main switch 15 and the back interlock switch 24: of the control relay 23 cooperate to connect the relay switch 26 between the control conductors 32 and 33. The switch 26 immediately closes to connect the operatingccil ot' the switch device 16 between the control conductors and 33. through the back interlock switch 17 l The switch 16 thereupon closes to connect the feeder circuit 10 to the auxiliary bus.

It the system supervisor desires to lock out the feeder entirely by disconnecting it from the auxiliary bus 12 also, he will eilect the energization of thelock-out relay 53 which, in turn, will encrg as a relay 55) between conductors 37 and ob. The relay 59 upon being energized, closes its switch which then coolwratcs with switch 56 of relay 55 and switch 58 of ret-ransfer relay 5% to maintain'a holding circuit for the relay 59 by connecting the relay 59 between the 59 also closes. its switch (31 whic hshort circui the operating: coil of the control relay 26 that ciated with the switch device 16. Since the relay 59 holds itself in, the short circuit is maintained until thesupervisor deener izes the relay 59 by energizing the relay 04-.

It the system supervisor desires to retransfer the feeder circuit from the auxiliary bus to the main bus or to connect the feeder circuit to the main bus after it has been 59, orthe relay alone, as the case may be.

Immediately after the decnergization of the relays and 59, their respective switches 57 and (31 are opened to remove the short circuits across the operating coils of the control relays 23 and 26, respectively. The control relay 23 may now be energized, and since the current element of the resistancemeasuring relay is not energized and the voltage element is energized; the switch 48 will be closed to connect the control relay 23 between the control conductors 35 and 3G. Switch of the control relay 23 thereupon cooperates with back interlock switch 15), of the switch 16, to reconnect the operating coil of the main switch 15 between the ctmtrol conductors 32 and 33.

It the system supervisor should desire to disconnect the resistor that is normally connected between the main bus and the auxiliary bus he will energize a relay 62 which connectsa relay (53 between the control conductors 37 and 38. The relay (53 closes its switch (it to maintain a holding circuit for itself through a relay switch 65 and closes another switch 66 to short circuit the operating coil of the relay 42 which thereupon opens to dcencrgize the switch 40. The switch =10, in openin", disconnects the resistor from the main bus 11 and opens the lrcuit therethrrmgh.

The resistor may be reconnected by operating the relay 65 to open the circuit of the relay 63 which is then deenergized to remove the short circuit across the coil of relay 42. Relay 42 then operates to enerswitch 40 to reconnect the resistor 13 between the main and'the auxiliary buses.

The feeder circuit is thus normally connected to the main bus until abnormal conditions occur in the circuit. The circuit is then transferred to the auxiliary bus; until the abnormal conditions are cleared and the connected load attain limit the load current to a safe value. hen such conditions are attained. the

feeder circuit is autmnatically transferred to the main bus. I

It excessive heating should be developed in the resistor connm-tcd between both alue that will I the tluerlnally-responsive element will disconnect the resistor to prevent an ll'ljllly resistance-measuring relay 4-5 between the auxiliary bus' and the faulty feeder circuit.

By means of the current element e6, variations in the torque of the voltage element 47 are compensated for when such variations are caused by fluctuation ofthe voltage of the auxiliary bus.

My invention is not limited to the arrangment shown, since various'changes may be made in the employment of different elements or in the arrangement thereof without departing from the spirit and scope of the invention, as set forth in the appended claims.

I claim as my invention:

1. Ina systen'i of distribution, the combination with a main supply bus, an auxiliary supply bus, means for connecting the auxiliary bus to the main bus comprising a load-limitng rcsitsor and a circuit interrupter connected in series therewith, a feeder circuit, and connecting means between the feeder circuit and each of the supply buses, of means for normally maintaining the connecting means between the feeder circuit and the main supply bus closed and the connecting means between the feeder circuit and the auxiliary supply bus open, means for normally maintaining the circuit between the main and auxiliary buses through the load-limitingresistor closed, means for opening the connecting means between the feeder circuit and the main supply bus and closing the connecting means between the coder circuit and the auxiliary supply bus when a short-circuit occurs on the feeder circuit, whereby a reduced current is sup-.

main and auxiliary buses when a predetermined temperature condltion exists in said resistor.

2. The combination in a distribution system with a feeder circuit and main and auxiliary supply buses, of means for transferring the feeder circuit from the main sup ply bus to the auxiliary supply bus on the occurrence of a short circuit on the feeder circuit, means for connecting the two buses whereby a reduced current is supplied to said feeder from the main bus, comprising a load-limiting device and a circuit interrupter, means for normally maintainingsaid circuit interrupter closed, and means f pen g th i ter upte when th t a perature of saidloadlimiting device reaches a predetermined value. p

The combination with a main supply bus, an auxiliary supply bus and a feeder circuit to be energized therefrom, of'a resistor, means for connecting the resistor between both buses so that a limited current may flow from the main bus .to the auxiliary bus, means energized from the feeder .cir

cuit upon the occurrence of abnormal conditions therein to transfer thefeeder circuit fro-m the main to the auxiliary bus, and means foropening the resistor-connecting means depending upon the temperature developed in the resistor by the currents supplied therethrough to the feeder circuit from the main bus.

4. The combination. with a feeder circuit and main and auxiliary supply buses, of means for transferring the feeder circuit .from themain supply bus to the auxiliary supplybus when a short-circuit occurs on the feeder'circuit, means for retransferring the feeder circuit to the first supply'bus when the resistance of the feeder circuit and the load connected thereto attains a predetermined value. meansfor connecting means for opening the interrupter in ac cordance with the temperature of said leadlimiting device.

5. The combination with a feeder circuit and main auxiliary supply buses, of means fortransferringthe feeder circuit from the main supply bus to the auxiliary supply bus on the occurrence of an overload on the feeder circuit, means for connecting the two buses so that the main bus may supply a limited current to the auxiliary bus comprising a load-limiting device anda circuit interrupter, and means for opening said cir-' cuit interrupter when said load-limiting device attains a predetermined temperature and for reclo sing said circuit interrupter when the temperature of, said loadlimiting device falls below a predetermined value.

, 6. The combination with a feeder circuit and main and auxiliary supply buses, of means for transferring the feeder circuit from the main supply bus to the auxiliary supply bus when a short-circuit occurs on the feeder circuit, means for retransfcrring the feeder circuit to the first supply bus when the resistanceof the feeder circuit and the load connected thereto attains a predetermined value, meansfor connecting the two buses comprising a load-limiting device and a circuit interrupter, whereby a reduced current flows from the main bus to the auxiliary bus, and means for opening said circuit interrupter when said load-limiting device attains a predetermined temperature and for reclosing said circuit interrupter when the temperature of said load-limiting device falls below a predetermined value.

7. In a system of distribution, the combination with a main bus, an auxiliary bus and a plurality of feeder circuits to be energized therefrom, of resistance means con nected between both buses to conduct a limited current to the auxiliary bus, means subscribed my name this 28th day of Sep- 0 tcmber, 1923. r a

MAURICE E. REAGAN. 

